We are using two promising MR techniques Susceptibility- Weighted Imaging (SWI) and Magnetic Resonance Spectroscopic Imaging (MRSI), acquired early after TBI to determine whether they are better at evaluating TBI severity by showing that injury is present in brain that appears normal with conventional MRI and that SWI/MRSI individually or combined will better predict 3- and 12-month neurological (NL) and neuropsychological (NP) outcome. In this revision application, we propose adding DTI to our imaging protocol. DTI provides additional information regarding the degree and directionality of tissue water diffusion;the apparent diffusion coefficient (ADC), fractional anisotropy (FA), and axial diffusivity (||) all of which decrease with axonal injury that reflects disturbed water diffusion along white matter tracts and radial diffusivity () which increases with injury and reflects increased water diffusion across axonal fibers We will acquire 3D SWI/MRSI/DTI to evaluate 11 brain regions in 90 children (4-18 years) with moderate/severe (GCS<13) TBI, 7-17 days after injury and 90 controls. Measurements will be compared regionally, globally (all regions combined) and as 3 pooled brain regions (cortical, subcortical, and posterior fossa). Our aims are to: 1) demonstrate that DTI parameters will detect axonal injury and improve 3 and 12- month NL/NP outcome prediction compared to clinical indicators;2) determine whether SWI/MRSI/DTI data individually or in combination are more accurate for predicting outcome;and 3) repeat SWI/MRSI/DTI at 12 months to categorize patterns of injury, defined as neuronal degeneration, recovery and plasticity measured by interval changes of NAA or DTI parameters associated with global functional outcomes and to explore whether hemorrhagic SWI lesions are still present. Current imaging techniques fail to recognize the extent of TBI in children and as a result, this has significant untoward effects regarding understanding the true severity of injury, making treatment decisions and in being able to predict prognosis. Adding DTI will provide additional direct measures of axonal injury and additional information to evaluate children with TBI. PUBLIC HEALTH RELEVANCE: Current imaging techniques underestimate or fail to recognize the extent of TBI in children which has significant untoward effects regarding understanding the true severity of injury. Diffusion Tensor Imaging will be used with other more sensitive imaging techniques (SWI and MRSI) to improve injury detection in brain that may appear normal. We believe that success of this grant will result in a paradigm shift in how children will be evaluated after TBI that will improve neurological outcome and quality of life.